Relief valve



K. w. NoLAN RELIEF VALVE lFeb. 1s, 1947.

' Filed June 22, 1945 Patented Feb. 18, 1947 RELIEF VALVE Kenneth William Nolan, East Perth, Western Australia, Australia Application June 22, 1945, Serial No. 600,944 In Australia February 21, 1944 2 claims. (c1. 137-53) This invention relates to improvements in the relief valves of hydraulic systems for operating machines.

The invention more specifically concerns an improved adjustable relief valve and a pressure reservoir associated therewith adapted to smooth out the pump impulses.

The invention consists broadly of a container or reservoir that under pressure has one `part acting as a diaphragm so that the movement under pressure duly opens the relief valve at the predetermined pressure. The container or pressure reservoir simultaneously functions to smooth' out the impulses generated by the hydraulic pump if this is of the piston type.

The invention will readily be understood by reference to the accompanying drawing showing the apparatus in sectional elevation.

As shown in the drawing, there is an oil pres. sure box or reservoir I which need have no considerable capacity, but which must be built of material sufficiently strong to withstand the maximum pressure generated by the pump, and which in one part at least will respond to increasing pressure by exing suiliciently so as to act as a diaphragm. This increase in capacity causedby the diaphragm action serves very efliciently to smooth out the pump impulses, particularly if the hydraulic pump is of the vpiston type. Attached to or integral with the pressure reservoir is the body I I of the relief valve. Inside this relief valve fits a valve piston I2. This piston at one end is engaged against a screw control sleeve member I3, the function of which will subsequently become apparent. Inside the valve piston I2 there is an cil duct I4 communicating with the interior of the reservoir and also in communication (unless this is prevented) with another oil duct I5 that passes out of the end of the piston and communicates with an oil duct I6 in the control sleeve. Adapted to move inside an extension of the oil duct I5 is a valve spindle Il that extends out into the reservoir and terminates Vin a foot member I8. Between the foot member I8 and the end of the valve piston I2 is placed a stout spring I9 that has the effect of keeping the valve foot I8 up against the side of the box, or more conveniently against a stop member 20 provided for this purpose. The spring also acts to maintain the valve piston I2 against the end of the control sleeve I3. In the drawing, the inlet for the oil is referenced 2I and the outlet may be at any convenient point or as indicated at 22.

The apparatus operates as follows.

Oil enters the pressure box I0 through the inlet 2l and normally passes out through the outlet 22, to the means actuating the hydraulic feed. The considerable pressure generated serves to some extent to flex the material of the reservoir and this smooths out the impulses of the hydraulic pump, particularly if this is of the piston type. When the pressure reaches the predetermined level, the effect is that one side or both opposite sides of the reservoir acts as a diaphragm and the distance between the sides is increased. The effect of this is that under the influence of the spring I9 the relative position of the valve spindle Il inside the extension of the duct I5 isv changed. In other words, the valve spindle moves in the duct and ultimately uncovers the communication between the ducts I4 and I5. When this happens, oil escapes through the duct I6 and the pressure is relieved until a state of balance is reached.

It will be obvious that the further the control sleeve I3 is screwed in, the greater distance will the valve spindle Il have to travel before the communication between the ducts I4 and I5 is established. In other words, screwing in of the control sleeve I3 increases the pressure that must be reached before oil is by-passed through the relief valve.

I claim:

1. Improvements in and relating to relief valves of hydraulic systems for operating ma.- chines comprising the combination of a container or reservoir that under pressure has at least one side acting as a diaphragm; an inlet for said reservoir, a valve body connected to one side of said reservoir; a valve piston movable inside the valve body; a control member that can be screwed on the valve body so as to press against and control the position of the valve piston; one intercommunicating ducts in the valve piston ;l one duct communicating with the interior of the reservoir and the other duct providing an outlet, a valve spindle engaging'the other side of the reservoir and adapted to move in an extension of one of these ducts and to control communication between the two ducts in response to the relative movements of the walls of the reservoir; and a spring that abuts at one of its ends against an extension of the valve spindle and at its other end against the valve piston.

2. Improvements in and relating to relief valves of hydraulic systems for operating machines as' set out in claim 1, in which the `control member 2,416,205 Y y s Y has a, duct providing communication between the outlet duct of the valve piston and the exterior 1 Number UNITED STATES PATENTS of the reservoir.v Name Date 1,236,583 Manning Aug. 14, 1917 KENNETH WIT-MAM NOLAN- 5 1,315,394 Boosey July 21, 1931 1,502,739 Munzingery July 29, 1924 REFERENCES CITED 1,776,937 Timbs sep1.3o, 1930 The following references are of record in `the 1,207,882 Dorff V v. `Dec, 12, 1916 1 le of 'this'patentz f 2251g2`75 Ernst Aug. 5, 1941 

